The antioxidants such as t-Butylhydroxyanisol (BHA), t-butylhydroxy toluene (BHT), and ethoxyquin offer protection to mice from lung adenoma and other forms of cancer caused by the administration of benz(a)pyrene (BP) and dibenz(a,h)anthracene (DBA). However, the mechanism of this protection is not clear. The anti-carcinogenic effect of antioxidants could either be due to the activation of the enzyme systems (such as GSH-S-transferases) which are involved in the detoxification of highly electrophylic toxic metabolites of pro-carcinogens or the antioxidants are themselves metabolized by mixed function oxidases in the same manner as the carcinogens and the metabolites of antioxidants compete with 'ultimate' carcinogens for the binding with cellular macromolecules. The work proposed in this project is aimed at understanding the mechanism of the effect of anticarcinogenic action of antioxidants. The effect of oral administration of ethoxyquin, BHA and BHT will be studied on lung adenoma produced in mice by administration of BP and DBA. The effect of these compounds on the total GSH-S-Transferase of the lung and on the isozymic pattern of this enzyme will be studied. Besides kinetic characterization, immunochemical studies will be performed using antibodies raised against homogenous preparations of genetically distinct mouse lung GSH-S-transferases. Since in the mouse liver several genetically distinct isozymes are known, the effect of antioxidants on each one of the GSH-S-transferase isozymes of lung will be studied. GSH-S-transferase is known to bind chemical carcinogens, therefore, the binding of each of the mouse lung GSH-S-transferase and the metabolites of BA and BP will be studied. In addition, the effect of antioxidants on the mixed function oxidases which are responsible for the activation of chemical carcinogens and on the overall metabolism of GSH which provide in vivo substrate (GSH) for GSH-S-transferase will be studied. Metabolism of antioxidants by mixed function oxidases will be studied by incubating the antioxidants with microsomal fraction and by characterizing the metabolites using modern physico-chemical techniques. Effect of these metabolites on the binding of carcinogen and GSH-S-transferase will also be studied.